1. Field of Invention
The present invention relates generally to the field of infrared detecting devices and more particularly to the automatic standardized calibration of infrared detection devices.
2. Technical Background
Various methods have been employed to electronically control water flow through a water control device such as a faucet or spigot. Among the accepted and conventional methods is the use of an optical sensor for detecting reflections from an infrared (xe2x80x98IRxe2x80x99) source or IR emitter. Generally speaking, a pulsed IR beam is reflected from an object (such as a user""s hands) and sensed to determine whether to activate or deactivate a solenoid valve to control water flow from the water control device. When processing electronics determine the reflection has exceeded a threshold value, a control signal opens a solenoid valve. Pulsed IR sensing remains at the forefront of sensing techniques used with these types of devices due in part to its reasonable performance and low cost.
Because of variations in processing circuits, emitter characteristics and sensor characteristics, it is necessary to calibrate an IR system. Calibration of infrared sensing devices such as, for example, automatically activated flow control devices is labor intensive and inefficient with respect to devices presently on the market. The low cost IR sensing devices employed in automatically activated flow control devices vary with respect to power requirements, performance, and other criteria. As a result, readings taken by these IR sensing devices (such as whether a user""s hands are present beneath the aerator of a faucet) are generally non-uniform from device to device, and therefore often result in improper activation and deactivation of some devices. Similarly, as battery power for these devices decreases over time, so does the power output of the IR sensing devices. Moreover, water droplets sprayed or otherwise deposited on or near a lens or lens cover of an IR sensing device have been known to cause the IR sensing devices to malfunction. As a result, manual calibration of conventional IR sensing devices of automatically activated flow control devices is generally required on a frequent basis following extended periods of use. The repeated manual calibration can be time consuming and costly, particularly when the IR sensing devices are located in areas that are difficult to access.
The present invention generally provides a system and method for calibrating infrared detecting devices, which detect the presence of objects by detecting IR reflections. A system in accordance with an exemplary embodiment of the present invention includes calibrating the output of the IR detector by a control module, which receives the output of the IR detector and regulates the input of the IR emitter. The method eliminates or reduces the need to manually calibrate and adjust each IR detector and IR emitter that is part of the infrared detecting device. The control module repeatedly activates the IR emitter with an input value to emit IR radiation, which is reflected from an object in the surrounding environment to the IR detector. The output from the IR detector is transmitted to a control module. If the IR detector output is not within a standard range of values for randomly reflected infrared radiation, a calibration manager increases or decreases the input to the IR emitter. This process is repeated until the output of the IR detector is within the standard range of values. The value of the corresponding input to the IR emitter to maintain this value of the IR detector within the standard range of values is stored in the nonvolatile memory of the control module and the calibration manager reprograms itself to use this calibration value of input to the IR emitter as a reference standard.